Nonreciprocal charge transport at topological insulator/superconductor interface

Topological superconductor (TSC) is attracting growing interest for its potential application to topological quantum computation. The superconducting proximity effect on the topological insulator (TI) surface state is one promising way to yield the topological superconductivity. The superconductivity realized at the interface between TI Bi₂Te₃ and non-superconductor FeTe is one of such candidates because the mutual interaction between superconductivity and topological order is expected. Here, to detect the effect of spin-momentum locking in the Cooper pair, we investigate nonreciprocal transport; i.e. current-direction dependent resistance, which is sensitive to the broken inversion symmetry of the electronic state. The largely enhanced nonreciprocal phenomenon is detected in the Bi₂Te₃/FeTe heterostructure associated with the superconducting transition. The emergent nonreciprocal signal at low magnetic fields is attributed to the current-induced modulation of supercurrent density under in-plane magnetic fields perpendicular to current, exemplifying the close connection between the superconductivity and the topological electronic state at the interface.